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    <script>
        // 如何让 a==1&&a==2&&a==3     为true
        
        let i=1
            Object.defineProperty(Object.prototype,'a',{
                get(){ 
                    return  i++
                }
            })
            console.log(a==1&&a==2&&a==3)
            // 只要出现a，就会触发

    </script>
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